// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IPC_IPC_CHANNEL_WIN_H_
#define IPC_IPC_CHANNEL_WIN_H_

#include "ipc/ipc_channel.h"

#include <stdint.h>

#include <queue>
#include <string>

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_loop.h"
#include "base/win/scoped_handle.h"
#include "ipc/ipc_channel_reader.h"

namespace base {
class ThreadChecker;
}

namespace IPC {

class ChannelWin : public Channel,
                   public internal::ChannelReader,
                   public base::MessageLoopForIO::IOHandler {
public:
    // Mirror methods of Channel, see ipc_channel.h for description.
    // |broker| must outlive the newly created object.
    ChannelWin(const IPC::ChannelHandle& channel_handle,
        Mode mode,
        Listener* listener);
    ~ChannelWin() override;

    // Channel implementation
    bool Connect() override;
    void Close() override;
    bool Send(Message* message) override;
    AttachmentBroker* GetAttachmentBroker() override;
    base::ProcessId GetPeerPID() const override;
    base::ProcessId GetSelfPID() const override;

    static bool IsNamedServerInitialized(const std::string& channel_id);

private:
    // ChannelReader implementation.
    ReadState ReadData(char* buffer, int buffer_len, int* bytes_read) override;
    bool ShouldDispatchInputMessage(Message* msg) override;
    bool GetNonBrokeredAttachments(Message* msg) override;
    bool DidEmptyInputBuffers() override;
    void HandleInternalMessage(const Message& msg) override;
    base::ProcessId GetSenderPID() override;
    bool IsAttachmentBrokerEndpoint() override;

    static const base::string16 PipeName(const std::string& channel_id,
        int32_t* secret);
    bool CreatePipe(const IPC::ChannelHandle& channel_handle, Mode mode);

    bool ProcessConnection();
    bool ProcessOutgoingMessages(base::MessageLoopForIO::IOContext* context,
        DWORD bytes_written);

    // Returns |false| on channel error.
    // If |message| has brokerable attachments, those attachments are passed to
    // the AttachmentBroker (which in turn invokes Send()), so this method must
    // be re-entrant.
    // Adds |message| to |output_queue_| and calls ProcessOutgoingMessages().
    bool ProcessMessageForDelivery(Message* message);

    // Moves all messages from |prelim_queue_| to |output_queue_| by calling
    // ProcessMessageForDelivery().
    void FlushPrelimQueue();

    // MessageLoop::IOHandler implementation.
    void OnIOCompleted(base::MessageLoopForIO::IOContext* context,
        DWORD bytes_transfered,
        DWORD error) override;

private:
    struct State {
        explicit State(ChannelWin* channel);
        ~State();
        base::MessageLoopForIO::IOContext context;
        bool is_pending;
    };

    State input_state_;
    State output_state_;

    base::win::ScopedHandle pipe_;

    base::ProcessId peer_pid_;

    // Messages not yet ready to be sent are queued here. Messages removed from
    // this queue are placed in the output_queue_. The double queue is
    // unfortunate, but is necessary because messages with brokerable attachments
    // can generate multiple messages to be sent (possibly from other channels).
    // Some of these generated messages cannot be sent until |peer_pid_| has been
    // configured.
    // As soon as |peer_pid| has been configured, there is no longer any need for
    // |prelim_queue_|. All messages are flushed, and no new messages are added.
    std::queue<Message*> prelim_queue_;

    // Messages to be sent are queued here.
    std::queue<OutputElement*> output_queue_;

    // In server-mode, we have to wait for the client to connect before we
    // can begin reading.  We make use of the input_state_ when performing
    // the connect operation in overlapped mode.
    bool waiting_connect_;

    // This flag is set when processing incoming messages.  It is used to
    // avoid recursing through ProcessIncomingMessages, which could cause
    // problems.  TODO(darin): make this unnecessary
    bool processing_incoming_;

    // Determines if we should validate a client's secret on connection.
    bool validate_client_;

    // Tracks the lifetime of this object, for debugging purposes.
    uint32_t debug_flags_;

    // This is a unique per-channel value used to authenticate the client end of
    // a connection. If the value is non-zero, the client passes it in the hello
    // and the host validates. (We don't send the zero value fto preserve IPC
    // compatability with existing clients that don't validate the channel.)
    int32_t client_secret_;

    scoped_ptr<base::ThreadChecker> thread_check_;

    base::WeakPtrFactory<ChannelWin> weak_factory_;
    DISALLOW_COPY_AND_ASSIGN(ChannelWin);
};

} // namespace IPC

#endif // IPC_IPC_CHANNEL_WIN_H_
